Abstract
Treatment of massive rotator cuff tears can be challenging, especially when tears are considered irreparable or, when repaired, at significant risk of retear. A surgical technique is described using a biodegradable subacromial balloon-shaped spacer (InSpace; Ortho-Space, Caesarea, Israel) that, when implanted between the humeral head and acromion, permits smooth, frictionless gliding, supporting shoulder biomechanics. The specific insertion technique described herein is a simple procedure that can be performed in a day-care or outpatient setting with patients under local anesthesia, thus providing a treatment option for patients with multiple comorbidities complicating or contraindicating surgery, such as reverse arthroplasty under general anesthesia.
Rotator cuff tears (RCTs) are among the most common tendon injuries seen in orthopaedic patients, resulting in significant pain and disability; tears can range in severity from partial to massive, with the latter often considered irreparable because direct repair at the point of tendon insertion may not be feasible despite extensive soft-tissue mobilization and release. There are a variety of treatments for massive RCTs, and the optimal treatment is controversial.1 In cases in which a massive RCT has been repaired, the primary repair has a relatively high chance of rerupture, with retear rates reported in between 20% and 65% of cases over time.1 Irreparable RCTs are typically defined by the tear size, presence of tendon retraction, chronicity of the injury, condition of the rotator cuff musculature including the extent of muscle atrophy, and degree of fatty infiltration.2 A novel surgical technique for treating massive, irreparable RCTs is described; it uses an inflatable, biodegradable, subacromial balloon-shaped spacer, the InSpace system (Ortho-Space, Caesarea, Israel). Placement of the balloon between the acromion and the humeral head permits smooth and frictionless gliding, thereby assisting in the restoration of shoulder biomechanics and pain reduction in the majority of treated patients.
The InSpace system comprises an introducer and a preshaped spacer constructed of the copolymer poly(L-lactide-co-ɛ-caprolactone), a widely used biocompatible biomaterial that biodegrades within a 12-month period.3 The spacer is available in 3 sizes to accommodate individual patient anatomy and can be implanted either arthroscopically or as described herein, under fluoroscopic guidance using local anesthesia in a day-care setting.
Surgical Technique
The patient is placed in the beach-chair position (Video 1). Three-step local anesthesia is induced in the shoulder with 2% lidocaine and 2% bupivacaine injections. The first injection anesthetizes the skin and the soft tissues through to the medial base of the coracoid process by use of a dental anesthetic syringe (Citoject Stainless Steel; Heraeus Kulzer, Hanau, Germany). Once the anesthetic works, the same path is taken with a spinal needle aiming at the medial base of the coracoid and gliding tangentially to reach the suprascapular nerve. The second injection induces skin anesthesia at the lateral incision, which is identical to the anatomic location of a regular arthroscopic lateral port. The third injection, using a dental syringe, introduces the local anesthetic into the subacromial space.
The fourth injection provides additional anesthesia, medially at the anatomic point of the suprascapular nerve. Other local anesthetic techniques may be used per the surgeon's preference as long as effective anesthesia is achieved.
The fluoroscope (Ziehm Solo; Ziehm Imaging, Nuremberg, Germany) is positioned to attain a true anteroposterior (AP) view of the glenohumeral joint with good visualization of the acromio-humeral distance, preferably with the humeral shaft vertical on the screen.
The subacromial space is measured through the lateral 1- to 2-cm skin incision (as for a standard arthroscopic lateral portal incision) using 2 identical metal rods (Wissinger Rod, 4 mm [AR-3025]; Arthrex, Naples, FL): 1 to define the total length of the subacromial space and 1 to determine the required balloon size. Under fluoroscopic guidance, the first metal rod is inserted, 1 cm medially to the glenoid rim. The second metal rod is then inserted parallel to the first, until it reaches the lateral border of the greater tuberosity. Both positions are verified under fluoroscopic vision (Fig 1).
Fig 1.
Subacromial space measurement: fluoroscopic view of distance measurement using 2 identical metal rods. The distance is measured from 1 cm medial to the glenoid rim to the lateral border of the tuberosity. The difference between the 2 metal rods indicates the size of the required device.
The rods are then removed, keeping their relative locations, and the difference between the 2 rods is measured to determine the length between the glenoid rim and the lateral border of the greater tuberosity. This distance defines the required spacer size length that should be selected from the 3 available sizes, as shown in Table 1.
Table 1.
InSpace Spacer Size and Recommended Inflation Volumes
| Balloon Size | Width (mm) | Length (mm) | Maximum Volume (mL) for Device Spreading | Recommended Final Volume (mL) |
|---|---|---|---|---|
| Small | 40 | 50 | 15-17 | 9-11 |
| Medium | 50 | 60 | 22-24 | 14-16 |
| Large | 60 | 70 | 40 | 23-25 |
Before the device is introduced into the shoulder, the tract is expanded using a portal dilatator (Portal Dilatation Set [AR-6520S]; Arthrex) to enable easier insertion of the introducing tube. The tube is then inserted until it is 1 cm medial to the glenoid rim while following the direction of the scapular spine (to avoid a position that is too anterior or posterior). Correct positioning is verified using a lateral fluoroscopy view.
By use of the AP fluoroscopy position, positioning is confirmed by ensuring that the metal end of the delivery system, which connects to the balloon, is located at the lateral level of the tuberosity. The introducing tube should be placed approximately 1 cm over the glenoid rim (Fig 2).
Fig 2.
Confirmation of device insertion by fluoroscopic view: fluoroscopic true AP view of subacromial space of a patient in beach-chair position after insertion of device introducing tube into desire location in subacromial space. The tip of the tube is positioned over the glenoid rim, whereas the metal part is at the lateral border of the tuberosity.
When the device is properly positioned, the extension tubing (BD Connecta PVC Extension Tubing; BD, Franklin Lakes, NJ) is connected to the distal side of the 60-mL BD syringe with the BD Luer-Lok and then connected to the device handle. Before device inflation, the protecting tube should be removed carefully by pulling it backward without changing the device position. Then the device is slowly inflated to its maximum volume per the balloon-size volume, as described in Table 1. During inflation, the humeral head's downward displacement can be followed fluoroscopically, which ensures that the balloon is properly placed.
Because no debridement or soft-tissue cleaning of the subacromial space is performed with this surgical technique, the maximum volume required to correctly inflate the balloon may be reduced to approximately 70% of the maximum volume described in Table 1.
After completion of the device's spreading, the valve should remain open to permit backflow of saline solution into the syringe until the recommended inflation volume according to Table 1 is achieved. The recommended volume ensures that the subacromial space is not overstuffed. At this stage, the humeral head moves back superiorly but not all the way as seen before balloon insertion.
It is important to use the recommended volume because over-inflation may result in tension in the deltoid muscle with resulting pain and an increased likelihood of device displacement. Table 2 shows additional tips and pitfalls.
Table 2.
Technical Tips and Pitfalls for Fluoroscopy-Guided Implantation
| Tips | Pitfalls |
|---|---|
| There is no need to perform subacromial bursectomy because the balloon acts as a dissection and spacer. | If starting the procedure before local anesthesia is under effect (i.e., relaxation of patient), the subacromial space might be reduced because of deltoid contraction. |
| If the measurement of the space falls between the device sizes, the surgeon should always select the smaller size (e.g., if the measurement is 55 mm, one should select medium and not large). | An oversized device (because of either the size or over-inflation) may cause increased subacromial pressure with subsequent pain. |
| The surgeon should use a surgical instrument (e.g., scissors) to enlarge the lateral portal before inserting the device. | The surgeon should make sure there is no kink in the protecting sheath due to forceful insertion. |
| Slow inflation of the balloon will reduce pain during device inflation (i.e., tissue dissection). | If patient feels pain during inflation, muscle contraction may prevent proper spreading of the balloon. |
| The surgeon should not over-inflate the device. To spread the device, it is sufficient to inflate it to 70% of the recommended maximum volume specified in the instructions for use. | Over-inflation of the device may cause pressure on the humeral head and cause pain during and after the procedure. It can be monitored by viewing humeral head reduction on the fluoroscopy screen. |
The balloon is then sealed and secured in situ by sliding forward the red safety button and rotating the green knob clockwise, as described in the InSpace system instructions for use. The delivery system is removed and the skin closed.
One should verify fluoroscopically that there is some humeral head reduction (Fig 3) and that the balloon is accurately placed and stable when the shoulder is passively moved through a full range of movement.
Fig 3.
Confirmation of placement: fluoroscopic true AP view of subacromial space of a patient in beach-chair position at end of implantation procedure. The spacer is fully inflated with saline solution and placed between the acromion and the humeral head. The acromiohumeral distance is enlarged compared with the pre-implantation distance.
Discussion
RCTs are frequent, and their incidence increases with age. They affect over 50% of individuals aged older than 60 years. Although some patients may have a painless, normally functioning shoulder despite the presence of an RCT, the functional implications of a tear can dramatically affect the patient's daily life.
Although surgical repair can produce excellent results, the massive, contracted, immobile RCT presents a significant challenge for the surgeon, requiring sophisticated surgical techniques. A range of surgical options are available, including debridement (with or without partial tendon repair), tendon transfer, muscle-tendon sliding procedures, use of rotator cuff allografts and synthetic graft materials, arthrodesis or arthroplasty, and reverse arthroplasty or hemiarthroplasty.4-6 There are, however, no consensus or definitive guidelines on the preferred surgical option to treat this challenging patient population.7 Furthermore, despite these treatment options, the retear rate of massive tears after a primary repair is between 20% and 65%.1 As the age of patients with massive tears rises, an additional challenge exists because of the coexistence of significant comorbidities that significantly increase patients' risk of undergoing a surgical procedure under general anesthesia; indeed, general anesthesia may be a contraindication to such surgery.
The InSpace biodegradable, balloon-shaped spacer provides a simple and clinically effective means of treating RCTs; a particular advantage of the system is the ability to place the balloon without the need for a general anesthetic. It therefore provides the surgeon with a valuable treatment option in this most challenging patient population because the balloon-shaped spacer can be placed under fluoroscopic guidance with patients under local anesthesia. The procedure can be performed on a day-surgery or outpatient basis, requiring no hospitalization.
Use of the innovative InSpace device has been reported as an arthroscopic technique,8 and a clinical study of 20 patients with massive irreparable RCTs (11 men and 9 women; mean age, 70.5 years; age range, 54 to 85 years) with a 3-year postoperative follow-up period showed significant improvement in total Constant score (P < .0001) at final follow-up.9
The fluoroscopy-guided insertion of the InSpace spacer with patients under local anesthesia provides a simple, minimally invasive option for treatment of massive RCTs. Furthermore, the technique provides a low-risk, clinically effective option for an elderly patient population disabled by massive cuff tears but for whom surgery such as reverse arthroplasty is high risk because of multiple medical factors and comorbidities that significantly increase their risk when undergoing routine surgical procedures under general anesthesia.
The InSpace system is designed to reduce friction between the acromion and humeral head or rotator cuff, reducing the pain and morbidity associated with tendon pathology for a demonstrated minimum of up to 3 years after implantation. Limitations of the spacer include treatment of the correct patient population, that is, patients without significant osteoarthritis and with preserved passive motion. When the system is used in this patient population, the spacer offers a safe and effective option for patients with massive, irreparable RCTs who are unwilling or unable for medical reasons to undergo general anesthesia or demanding surgical procedures; the InSpace device can be simply and easily inserted under fluoroscopic guidance with patients under local anesthesia on a day-care basis.
Footnotes
The authors report the following potential conflict of interest or source of funding: E.G. and E.C. receive support as follows: free-of-charge devices were provided to the Latisana Civil Hospital by the company to conduct the device implantations. A.D. reports that he works as a Medical Director and Board Member of the device manufacturing company, Ortho-Space Ltd. The remaining authors declare that they have no relevant financial interests.
Supplementary Data
Local anesthesia using 2% lidocaine and 2% Marcaine was induced by an anterior approach with the suprascapular nerve anesthetized. Then, from a lateral approach, the skin incision was anesthetized, and a deeper approach was used for subacromial space anesthesia. The operating room setting includes the patient in the beach-chair position with the fluoroscope in the AP position. A lateral skin incision was used in exactly the same area of a lateral portal for arthroscopic positioning. The skin incision was widened with a surgical tool. The tool was replaced by a metal rod going all the way into the subacromial space, and an identical metal rod was used to verify the required size of the device, by measuring the difference between the 2 metal rods. The metal rod was then replaced by the InSpace system (using the same route as the metal rod going all the way into the subacromial space), with verification of the position by fluoroscopy. Once positioned, the device was inflated with regular saline solution. Because the device is slowly inflated, the patient does not feel discomfort. Once the recommended inflation volume was reached, the device was locked and sealed in situ, and the device stability and position were verified and confirmed by fluoroscopy.
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Associated Data
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Supplementary Materials
Local anesthesia using 2% lidocaine and 2% Marcaine was induced by an anterior approach with the suprascapular nerve anesthetized. Then, from a lateral approach, the skin incision was anesthetized, and a deeper approach was used for subacromial space anesthesia. The operating room setting includes the patient in the beach-chair position with the fluoroscope in the AP position. A lateral skin incision was used in exactly the same area of a lateral portal for arthroscopic positioning. The skin incision was widened with a surgical tool. The tool was replaced by a metal rod going all the way into the subacromial space, and an identical metal rod was used to verify the required size of the device, by measuring the difference between the 2 metal rods. The metal rod was then replaced by the InSpace system (using the same route as the metal rod going all the way into the subacromial space), with verification of the position by fluoroscopy. Once positioned, the device was inflated with regular saline solution. Because the device is slowly inflated, the patient does not feel discomfort. Once the recommended inflation volume was reached, the device was locked and sealed in situ, and the device stability and position were verified and confirmed by fluoroscopy.